Rare earth based hydrogen storage alloy and application thereof

Info

Patent number: 10566614
Type: Grant
Filed: Aug 27, 2015
Date of Patent: Feb 18, 2020
Patent Publication Number: 20170288217
Assignees: Baotou Research Institute of Rare Earths (Baotou, Neimenggu), National Engineering Research Centre of Rare Earth Metallurgy and Function Materials (Baotou, Neimenggu), Tianjin Baogang Research Institute of Rare Earths Co., Ltd. (Tianjin)
Inventors: Huizhong Yan (Baotou), Li Wang (Baotou), Wei Xiong (Baotou), Baoquan Li (Baotou), Jin Li (Baotou)
Primary Examiner: Anita Nassiri-Motlagh
Application Number: 15/507,133

Abstract

The invention relates to a rare earth based hydrogen storage alloy, represented by the general formula (I): RExYyNiz-a-b-cMnaAlbMcZrATiB (I) wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W. The alloy has favorable pressure-composition-temperature characteristic, high hydrogen storage capacity, high electrochemical capacity. The alloy doesn't contain magnesium element, and the preparation process of the alloy is easy and safe.

Description

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is the U.S. national phase of International Application No. PCT/CN2015/088274, filed on Aug. 27, 2015, which claims priority from Chinese Application Nos. 201410427179.9, 201410427199.6, 201410427220.2, 201410427259.4, 201410427281.9, 201410429187.7, and 201410429202.8, all filed on Aug. 28, 2014, the disclosures of which are incorporated herein by reference in their entireties for all purposes.

TECHNICAL FIELD

The invention belongs to the field of hydrogen storage alloy, and relates to a rare earth based hydrogen storage alloy and the application thereof.

BACKGROUND

Hydrogen storage alloy is a functional material with high hydrogen-storage density. At present, hydrogen storage alloy could be roughly divided into six categories: rare earth based AB₅type, such as LaNi₅; magnesium based, such as Mg₂Ni, MgNi, La₂Mg₁₇; rare earth-magnesium-nickel based AB_3-4type, such as La₂MgNi₉, La₅Mg₂Ni₂₃, La₃MgNi₁₄; titanium based AB type, such as TiNi, TiFe; zirconium or titanium based AB₂type with Laves phase, such as ZrNi₂; vanadium based solid solution type as (V_0.9Ti_0.1)_1-xFe_x.

The hydrogen-storage material widely used nowadays is LaNi₅type hydrogen-storage alloy. The alloy is mainly used as a negative material of a metal hydride-nickel(MH-Ni) secondary battery, with a theoretical electrochemical capacity of about 373 mAh·g⁻¹. The commercial negative material electrode materials in actual application is Mm(NiCoMnAl)₅(wherein Mm denotes mixed rare earths), which has a maximum capacity of 350 mAh·g⁻¹. In order to develop hydrogen-storage alloys with better electrochemical properties or higher hydrogen storage capacity, the research of magnesium based alloy has become a hotspot. Magnesium based alloys have high theoretical capacity. Especially, great progresses have been made in the study of rare earth-magnesium-nickel based AB₃type, A₂B₇type and A₅B₁₉type alloys and these alloys has been put into industrial application. Titanium, zirconium and vanadium based hydrogen storage materials were not widely used due to their disadvantages such as poor activation characteristic, high cost, etc.

CN201310228766.0 discloses an A₂B₇type hydrogen storage alloy for nickel-hydride battery and preparation method thereof. The composition of the alloy conforms to the general formula Ln_aMg_bNi_xY_yZ_z, wherein Ln denotes one or more rare earth element(s), Y denotes one or more element(s) selected from Al, Co, Nb, V, Fe, Cu, Zn, As, Ga, Mo, Sn, In, W, Si and P, and Z denotes one or more element(s) selected from Ag, Sr, Ge, 0.5≤a<2, 0<b<1, 5<X+Y+Z<9, 0<Y<3, 0<Z<1.

CN101210294A discloses a A₅B₁₉type alloy. The alloy has a formula of X_5-aY_aZ_b, wherein X denotes one or more of rear earth metals, Y denotes one or more of alkaline earth metal(s), Z denotes one or more element(s) selected from Mn, Al, V, Fe, Si, Sn, Ni, Co, Cr, Cu, Mo, Zn and B, 0<a≤2, 17.5≤b≤22.5.

CN102195041A discloses a hydrogen storage alloy for an alkaline storage battery. The alloy has a formula of La_xRe_yMg_1-x-yNi_n-m-vAl_mT_v, wherein Re denotes at least one rare earth element(s) including Y(ytterbium)(except La), T denotes at least one element(s) selected from Co, Mn and Zn; 0.17≤x≤0.64, 3.5≤n≤3.8, 0.06≤m≤0.22, v≥0. The main phase of the alloy is A₅B₁₉type crystal structure.

CN101238231A discloses a hydrogen storage alloy. The alloy contains a phase of Pr₅Co₁₉type crystal structure, which conforms to the general formula A_(4−w)B_(1+w)C₁₉, wherein A denotes one or more element(s) selected from rare earth elements including Y (yttrium); B denotes Mg element; C denotes one or more element(s) selected from Ni, Co, Mn, and Al; and w denotes a numeral in a range from −0.1 to 0.8; and the alloy have a composition as a whole defined by the general formula R1_xR2_yR3_z, wherein 15.8≤x≤17.8, 3.4≤y≤5.0, 78.8≤z≤79.6, and x+y+z=100; R1 denotes one or more element(s) selected from rare earth elements including Y (yttrium); R2 denotes an Mg element, R3 denotes one or more element(s) selected from Ni, Co, Mn, and Al; z is 0.5 or higher when it denotes the stoichiometric number of Mn+Al; z is 4.1 or lower when it denotes the stoichiometric number of Al.

CN102660700A discloses an AB₃type hydrogen storage alloy and preparation method thereof. The chemical formula of the AB₃type hydrogen storage alloy is La_0.35Pr_0.30Mg_xNi_2.90Al_0.30, wherein x=0.30˜0.35.

CN102195041A discloses a hydrogen storage alloy for an alkaline storage battery, the composition of which conforms to the general formula La_xRe_yMg_1-x-yNi_n-m-vAl_mT_v(Re: rare earth elements including Y; T: Co, Mn, Zn; 0.17≤x≤0.64, 3.5≤n≤3.8, 0.06≤m≤0.22, v≥0), and the alloy's main phase has a A₅B₁₉-type crystal structure.

CN103326004A discloses an A₂B₇hydrogen storage alloy for a nickel metal hydride battery and preparation method thereof. The alloy conforms to the structural general formula: Ln_aMg_bNi_xY_yZ_z, wherein Ln denotes at least one element selected from rare earth elements; Y denotes least one element selected from Al, Co, Nb, V, Fe, Cu, Zn, As, Ga, Mo, Sn, In, W, Si and P; Z denotes at least one element selected from Ag, Sr and Ge; 0.5≤a<2, 0<b<1, 5<X+Y+Z<9, 0<Y<3, 0<Z<1.

The above alloys do not contain Y element, or do not contain Zr element, or do not contain Ti element. However, they all contain alkaline earth metals or magnesium element. Because the vapor pressure of active metal element magnesium is high, the difficulty of manufacturing the alloy is increased, and the composition of the alloy is difficult to control. The escaped micro-fine magnesium powder is flammable and combustible, which is a potential safety hazards.

Researches of “An electrochemical study of new La_1-xCe_xY₂Ni₉(0≤x≤1) hydrogen storage alloys” (Electrochimica Acta, 46 (2001): 2385-2393) and “New ternary intermetallic compounds belonging to the R—Y—Ni(R═La, Ce) system as negative material electrodes for Ni-MH batteries” (Journal of Alloys and Compounds, 330-332 (2002): 782-786) report an AB₃type La—Y—Ni hydrogen storage alloy. Nevertheless, the alloy doesn't contain Mn and Al, and its maximum hydrogen storage capacity is only 260 mAh·g⁻¹.

SUMMARY

An object of the invention is to provide a rare earth based hydrogen storage alloy with high hydrogen storage capacity. Another object of the invention is to provide a rare earth based hydrogen storage alloy with high electrochemical capacity. Another object of the invention is to provide a rare earth based hydrogen storage alloy which is easy to prepare, or the composition of which is easy to control, or the preparation process of which is safe.

In order to achieve one or more of the above objects, according to the first aspect of the present application, provided is a rare earth based hydrogen storage alloy represented by the general formula (I):
RE_xY_yNi_z-a-b-cMn_aAl_bM_cZr_ATi_B (I)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W; x>0, y≥0.5, x+y=3, 13≥z≥7; 6≥a+b>0, 5≥c≥0, 4≥A+B≥0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), x>0, y≥0.5, x+y=3; 12.5≥z≥8.5; 5.5≥a+b>0, 3.5≥c≥0, 2.5≥A+B≥0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes La and/or Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes La.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes mischmetal consisting of La and Ce, preferably the atomic ratio of La and Ce is 0.8:0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes Lanthanum-rich mischmetal wherein La accounts for about 64 wt %, Ce accounts for about 25 wt %, Pr accounts for about 3 wt % and Nd accounts for about 8 wt %.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 2.5≥A+B>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 11>z≥9.5, 4.5≥a+b>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 12.5≥z≥11, 5.5≥a+b>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 9.5>z≥8.5; 3.5≥a+b>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A=B=0, c>0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 3.5≥a+b≥0; 3.0≥c>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0, 11>z≥9.5, 4.5≥a+b>0. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-1):
RE_xY_yNi_z-a-bMn_aAl_b (I-1)

wherein: RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; x>0, y≥0.5, x+y=3; 11>z≥9.5; 4.5≥a+b>0. When z=10.5, the hydrogen storage alloy is stoichiometric A₂B₇type; when z≠10.5, the hydrogen storage alloy is non-stoichiometric A₂B₇type.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≥x≥0.5, preferably 2.0≥x≥0.5, further preferably 1.2≥x≥0.8.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≥a≥0, preferably 2.5≥a≥0.5, further preferably 0.6≥a≥0.4.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 1.0≥b≥0, preferably 1.0≥b≥0.2, or preferably 0.3≥b≥0.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 10.8≥z≥9.5, preferably z=10.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.0≥x≥0.5, 2.5≥a≥0.5, 1.0≥b≥0.2, z=10.5.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0, 12.5≥z≥11. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-1):
RE_xY_yNi_z-a-bMn_aAl_b (I-1)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; x>0, y≥0.5, x+y=3; 12.5≥z≥11; 5.5≥a+b>0. When z=11.4, the hydrogen storage alloy is stoichiometric A₅B₁₉type; when z≠11.4, the hydrogen storage alloy is non-stoichiometric A₅B₁₉type.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≥x≥0.5, preferably 2.0≥x≥0.5, further preferably 1.5≥x≥1.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 3.0≥a≥0, preferably 3.0≥a≥0.5, further preferably 1.0≥a≥0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 1.5≥b≥0, preferably 1.5≥b≥0.3, further preferably 0.5≥b≥0;

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 12.5≥z≥11, preferably 11.4≥z≥11.0 further preferably z=11.4.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.0≥x≥0.5, 3.0≥a≥0.5, 1.5≥b≥0.3, z=11.4.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0, 9.5>z≥8.5; 3.5≥a+b>0. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-1):
RE_xY_yNi_z-a-bMn_aAl_b (I-1)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≥0.5, x+y=3; 9.5>z≥8.5, 3.5≥a+b>0. When z=9, the hydrogen storage alloy is stoichiometric AB₃type; when z≠9, the hydrogen storage alloy is non-stoichiometric AB₃type.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≥x≥0.5, preferably 2.0≥x≥0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2≥a≥0; preferably 2≥a≥0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 1.0≥b≥0, preferably 1.0≥b≥0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 9.5≥z≥8.5, preferably z=9.

In another further preferably embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.0≥x≥0.5, 2.0≥a≥0.5, 1.0≥b≥0.2, z=9.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes La and/or Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes La.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes mischmetal consisting of La and Ce, preferably wherein the atomic ratio of La and Ce is 0.8:0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes Lanthanum-rich mischmetal, La accounts for about 64 wt %, Ce accounts for about 25 wt %, Pr accounts for about 3 wt % and Nd accounts for about 8 wt %.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A=B=0, 3.5≥a+b≥0; 3.0≥c>0. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-2):
RE_xY_yNi_z-a-b-cMn_aAl_bM_c (I-2)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W; x>0, y≥0.5, x+y=3; 12.5≥z≥8.5, 3.5≥a+b>0, 3.0≥c>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.5≥x≥0.5, preferably 2.0≥x≥0.5, further preferably 1.2≥x≥1.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.0≥a≥0.5, preferably 1≥a≥0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 1.0≥b≥0.3; preferably 0.5≥b≥0.3.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 12.5≥z≥8.5, preferably 11.4≥z≥9, further preferably 11≥z≥10.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.5≥c≥0.1, preferably 1≥c≥0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.0≥x≥0.5, 2.0≥a≥0.5, 1.0≥b≥0.3, 2.5≥c≥0.1, 11.4≥z≥9.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes La and/or Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes La.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes mischmetal consisting of La and Ce, preferably the atomic ratio of La and Ce is 0.8:0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes Lanthanum-rich mischmetal, La accounts for about 64 wt %, Ce accounts for about 25 wt %, Pr accounts for about 3 wt % and Nd accounts for about 8 wt %.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 12.5≥z≥11, 4≥a+b>0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≥0.5, x+y=3; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 12.5≥z≥11 (when z=11.4, the alloy is stoichiometric A₅B₁₉type; when z≠11.4, the alloy is non-stoichiometric A₅B₁₉type), 4≥a+b>0, 3.5≥c≥0, 2.5≥A+B>0;

preferably, 2.5≥x≥0.5, further preferably, 2.0≥x≥0.5;

preferably, 2.5≥a≥0, further preferably, 2.5≥a≥0.5;

preferably, 1.0≥b≥0, further preferably, 1.0≥b≥0.2, still further preferably, 0.5≥b≥0;

preferably, 2.5≥a≥0.5, 1.0≥b≥0.2;

preferably, 2.5≥c≥0, further preferably, 2.5≥c≥0.1, still further preferably, 0.5≥c≥0;

preferably, 1.0≥A≥0, further preferably, 1.0≥A≥0.1, still further preferably, 0.5≥A≥0.1;

preferably, 1.0≥B≥0, further preferably, 1.0≥B≥0.1, still further preferably, 0.3≥B≥0;

preferably, z=11.4.

In a preferably embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 2.0≥x≥0.5, 2.5≥a≥0.5, 1.0≥b≥0.2, 2.5≥c≥0.1, 1.0≥A≥0.1, 1.0≥B≥0.1, z=11.4.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 11>z≥9.5; 3.5≥a+b>0; 3≥c≥0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≥0.5, x+y=3; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 11>z≥9.5 (when z=10.5, the alloy is stoichiometric A₂B₇type; when z≠10.5, the alloy is non-stoichiometric A₂B₇type), 3.5≥a+b>0, 3≥c≥0, 2≥A+B>0;

preferably 2.5≥x≥0.5, further preferably 2.0≥x≥0.5;

preferably 2.0≥a≥0, further preferably 2.0≥a≥0.5, further preferably 1.0≥a≥0.5;

preferably 1.0≥b≥0, further preferably 1.0≥b≥0.2, further preferably 0.5≥b≥0;

preferably 2.0≥c≥0, further preferably 2.0≥c≥0.1, further preferably 0.5≥c≥0;

preferably 1.0≥A≥0.1, further preferably 0.5≥A≥0.1;

preferably 1.0≥B≥0.1, further preferably 0.3≥B≥0.1;

preferably 10.8≥z≥9.5, further preferably z=10.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 2.0≥x≥0.5, 2.0≥a≥0.5, 1.0≥b≥0.2, 2.0≥c≥0.1, 1.0≥A≥0.1, 1.0≥B≥0.1, z=10.5.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 9.5>z≥8.5; 3≥a+b>0; 2.5≥c≥0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≥0.5, x+y=3; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 9.5>z≥8.5 (when z=9, the alloy is stoichiometric AB₃type; when z≠9, the alloy is non-stoichiometric AB₃type), 3≥a+b>0, 2.5≥c≥0, 2≥A+B>0;

preferably 2.5≥x≥0.5, further preferably 2.0≥x≥0.5, further preferably 1.2≥x≥0.8, for example, x=1;

preferably 2.0≥a≥0, further preferably 2.0≥a≥0.5, further preferably 0.6≥a≥0.4, for example, a=0.5;

preferably 1.0≥b≥0, further preferably 1.0≥b≥0.2, further preferably 0.5≥b≥0;

preferably 2.0≥c≥0, further preferably 2.0≥c≥0.1, further preferably 0.5≥c≥0;

preferably 1.0≥A≥0, further preferably 1.0≥A≥0.1, further preferably 0.5≥A≥0.1;

preferably 1.0≥B≥0, further preferably 1.0≥B≥0.1, further preferably 0.3≥B≥0.2;

preferably 9.4≥z≥8.5, further preferably 9.4≥z≥9, further preferably z=9.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm and Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V and W, 2.0≥x≥0.5, 2.0≥a≥0.5, 1.0≥b≥0.2, 2.0≥c≥0.1, 1.0≥A≥0.1, 1.0≥B≥0.1, z=9.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), x may be 0.1, 0.2, 0.3 or 0.4, x may also be 0.5, 0.6 or 0.7, x may also be 0.8, 0.9 or 1, x may also be 1.1, 1.2 or 1.3, x may also be 1.4, 1.5 or 1.6, x may also be 1.7, 1.8 or 1.9, x may also be 2, 2.1 or 2.2, x may also be 2.3, 2.4 or 2.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), y may be 0.5, 0.6 or 0.7, y may also be 0.8, 0.9 or 1, y may also be 1.1, 1.2 or 1.3, y may also be 1.4, 1.5 or 1.6, y may also be 1.7, 1.8 or 1.9, y may also be 2, 2.1 or 2.2, y may also be 2.3, 2.4 or 2.5, y may also be 2.6, 2.7, 2.8 or 2.9.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), a may be 0, a may also be 0.1, 0.2, 0.3, 0.4 or 0.5, a may also be 0.6, 0.7, 0.8, 0.9 or 1, a may also be 1.1, 1.2, 1.3, 1.4 or 1.5, a may also be 1.6, 1.7, 1.8, 1.9 or 2, a may also be 2.1, 2.2, 2.3, 2.4 or 2.5, a may also be 2.6, 2.7, 2.8, 2.9 or 3.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), b may be 0, b may also be 0.1, 0.2 or 0.3, b may also be 0.4, 0.5 or 0.6, b may also be 0.7, 0.8 or 0.9, b may also be 1.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), z may be 8.5, 8.6, 8.7, 8.8, 8.9 or 9, z may also be 9.1, 9.2, 9.3, 9.4 or 9.5, z may also be 9.6, 9.7, 9.8, 9.9 or 10, z may also be 10.1, 10.2, 10.3, 10.4 or 10.5, z may also be 10.6, 10.7, 10.8, 10.9 or 11, z may also be 11.1, 11.2, 11.3, 11.4 or 11.5, z may also be 11.6, 11.7, 11.8, 11.9 or 12, z may also be 12.1, 12.2, 12.3, 12.4 or 12.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c may be 0, c may also be 0.1, 0.2, 0.3, 0.4 or 0.5, c may also be 0.6, 0.7, 0.8, 0.9 or 1, c may also be 1.1, 1.2, 1.3, 1.4 or 1.5, c may also be 1.6, 1.7, 1.8, 1.9 or 2, c may also be 2.1, 2.2, 2.3, 2.4 or 2.5, c may also be 2.6, 2.7, 2.8, 2.9 or 3, c may also be 3.1, 3.2, 3.3, 3.4 or 3.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A may be 0, A may also be 0.1, 0.2 or 0.3, A may also be 0.4, 0.5 or 0.6, A may also be 0.7, 0.8 or 0.9, A may also be 1.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), B may be 0, B may also be 0.1, 0.2 or 0.3, B may also be 0.4, 0.5 or 0.6, B may also be 0.7, 0.8 or 0.9, B may also be 1.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), x may be 0.5, 1, 1.2, 1.5, 2 or 2.5, x may also be 1, 1.2 or 1.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), y may be 0.5, 1, 1.5, 1.8, 2 or 2.5, y may also be 1.5, 1.8 or 2.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), a may be 0, 0.5, 0.8, 1, 1.5, 2, 2.5 or 3, a may also be 0.5, 0.8, 1, 1.5, 2 or 2.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), b may be 0, 0.2, 0.3, 0.5, 0.8, 1 or 1.5, b may also be 0, 0.2, 0.3 or 0.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c may be 0, 0.1, 0.2, 0.5, 1, 1.5, 2 or 2.5, c may also be 0, 0.1 or 0.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A may be 0, 0.1, 0.2, 0.3, 0.5 or 1, A may also be 0.1, 0.3 or 0.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), B may be 0, 0.1, 0.2, 0.3, 0.5 or 1, B may also be 0, 0.1, 0.2 or 0.3.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), when z=9, the alloy is stoichiometric AB₃type; when z≠9, the alloy is non-stoichiometric AB₃type.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), when z=10.5, the alloy is stoichiometric A₂B₇type; z≠10.5, the alloy is non-stoichiometric A₂B₇type.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), when z=11.4, the alloy is stoichiometric A₅B₁₉type; z≠11.4, the alloy is non-stoichiometric A₅B₁₉type.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇, La₂Ni₇, LaNi₅, Ni₅Y, Ce₂Ni₇, Al₂Ni₆Y₃and LaY₂Ni₉.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇, La₂Ni₇, LaNi₅and Ce₂Ni₇.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇, La₂Ni₇, LaNi₅and Al₂Ni₆Y₃.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇and LaY₂Ni₉.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇and La₂Ni₇, Ni₅Y.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises LaY₂Ni₉phase.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇and La₂Ni₇.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) comprises Y₂Ni₇phase.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) has a maximum hydrogen storage capacity of 1.2˜1.5 wt %, preferably 1.3˜1.5 wt %, optionally 1.2˜1.4 wt % or 1.3˜1.4 wt %, at a temperature of 313K,

In an embodiment, when used as a negative material electrode for a Ni-MH battery, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) has a maximum discharge capacity of 300˜400 mAh/g, preferably 350˜400 mAh/g, further preferably 370˜400 mAh/g, still further preferably 380˜400 mAh/g, at a current density of 70 mA/g. The cut-off discharge voltage may be 1.0V.

In an embodiment, when used as a negative material electrode for a Ni-MH battery, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) has a capacity retention of more than 85%, preferably more than 90%, more preferably more than 95%, still further preferably more than 98% after 100 cycles of charge and discharge, at a current density of 70 mA/g. The cut-off discharge voltage may be 1.0V.

According to the second aspect of the present application, provided is use of the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention as a hydrogen storage medium.

According to the third aspect of the present application, provided is use of the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention in manufacturing an electrode of a secondary battery.

The rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention may be manufactured into electrode, and the electrode could be made into a secondary battery coupled with other suitable materials. The secondary battery made from the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention can be discharged and recharged for multiple times.

The rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention could be produced by a method comprising the following steps:

(i) providing raw materials according to the composition of the alloy product;

(ii) smelting the raw materials;

(iii) rapidly solidifying the smelted raw materials on a copper roller;

preferably, the linear speed of the copper roller in step (iii) is 3-4 m/s, and the copper roller is supplied with cooling water.

In an embodiment, in the method of preparing the rare earth based hydrogen storage alloy of the invention, after the step of rapidly solidifying, the prepared alloy is annealed at 700˜800° C. for 6˜10 hours, e.g. at 750° C. for 8 hours, under vacuum or inert gas.

In an embodiment, the hydrogen storage alloy of the invention may be produced by high temperature smelting-rapidly quenching method comprising the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching is 3.4 m/s. The copper roller is cooled with cooling water having a temperature of 25° C.

In an embodiment, in the method of preparing the rare earth based hydrogen storage alloy of the invention, the mass ratio of the raw materials which is prior to loss by burning are increased at an appropriate amount, the increase rate is shown in the following table:

raw material RE Y Mn Al increase rate 2% 1% 5% 3%

Besides the abovementioned methods, the hydrogen storage alloy represented by the general formula (I) of the invention may be produced by other methods for producing hydrogen storage alloys, such as: high-temperature smelting and casting method, mechanical alloying (MA) method, powder sintering method, high-temperature smelting and gas atomization method, reduction diffusion method, replacement-diffusion method, combustion synthesis (CS) method or self-propagating high temperature synthesis (SHS) method.

According to the fourth aspect of the invention, provided is the rare earth based hydrogen storage alloy represented by the general formula (I) as a hydrogen storage medium.

According to the fifth aspect of the invention, provided is the rare earth based hydrogen storage alloy represented by the general formula (I) for manufacturing an electrode of a secondary battery.

The rare earth based hydrogen storage alloy represented by the general formula (I) could be composited with other hydrogen storage alloys in various proportions to fabricate new hydrogen storage materials.

Heat treatment may be performed to improve the microstructures and properties of the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), for example, to relieve structural stresses and eliminate component segregation, or to improve hydrogen absorption/desorption plateau characteristics or discharge/charge plateau characteristics, or to increase hydrogen storage capacity and cycle life. Various surface treatments may be performed to improve the alloy's performance, such as to improve the kinetics performance of hydrogen absorption/desorption processes or charge/discharge processes of the alloy, or to enhance the antioxidant ability of the alloy, or to improve the electrical/thermal conductivity of the alloy.

In the invention, unless otherwise specified, symbols for elements are consistent with the Periodic Table of Elements. In the general formula (I) of the invention, Y denotes yttrium, Ni denotes nickel, Mn denotes manganese, Al denotes aluminum, Zr denotes zirconium and Ti denotes titanium.

The Beneficial Effects of the Invention

The rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention has one or more of the following advantage(s):

(1) It has a favorable pressure-composition-temperature (P-c-T) feature. Under normal conditions, the hydrogen storage capacity could reach 1.28 wt % or more, the maximum hydrogen storage capacity of the alloy could reach 1.36 wt % or more;

(2) The electrochemical performance and hydrogen gas absorption and desorption performance of the rare earth based hydrogen storage alloy of the invention as hydrogen storage electrode are better than the traditional LaNi₅type hydrogen storage alloy;

(3) The rare earth based hydrogen storage alloy of the invention doesn't contain magnesium, and therefore the preparation methods of the rare earth based hydrogen storage alloy of the invention is easier and safer compared to that of the traditional rare earth-magnesium-nickel hydrogen storage alloy

(4) The rare earth based hydrogen storage alloy of the invention has favorable activation performance, rate discharge ability, charging/discharging or hydrogen absorbing/desorbing cycling stability. It can work at a wide range of temperature and has a low self-discharge rate.

(5) One of the main components of the rare earth based hydrogen storage alloy of the invention is yttrium (Y). As Yttrium is abundant in rare earth minerals, the application of yttrium is beneficial for comprehensive utilization of rare earth resources of China.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are used to provide a further understanding of the invention and constitute a part of this application, in which:

FIG. 1-1 is an XRD pattern of the hydrogen storage alloy, LaCe_0.5Y_1.5Ni_9.7Mn_0.5Al_0.3(Example A23);

FIG. 1-2 is a redrawn XRD pattern of hydrogen storage alloy, LaCe_0.5Y_1.5Ni_9.7Mn_0.5Al_0.3according to the original XRD data of FIG. 1-1 (Example A23);

FIG. 1-3 is a P-c-T curve of the hydrogen storage alloy LaY₂Ni_9.5Mn_0.5Al_0.5(Example A13);

FIG. 2-1 is a XRD pattern of the hydrogen storage alloy LaY₂Ni_10.6Mn_0.5Al_0.3(Example B2);

FIG. 2-2 is a redrawn XRD pattern of the hydrogen storage alloy LaY₂Ni_10.6Mn_0.5Al_0.3according to the original XRD data of FIG. 2-1 (Example B2);

FIG. 2-3 is a P-c-T curve of the hydrogen storage alloy LaY₂Ni_10.6Mn_0.5Al_0.3(Example B2);

FIG. 3-1 is a XRD pattern of the hydrogen storage alloy LaY₂Ni₈Mn_0.5Al_0.5(Example C13);

FIG. 3-2 a redrawn XRD pattern of the hydrogen storage alloy LaY₂Ni₈Mn_0.5Al_0.5according to the original XRD data of FIG. 3-1 (Example C13);

FIG. 4-1 is a XRD pattern of the hydrogen storage alloy La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5(Example D28);

FIG. 4-2 a redrawn XRD pattern of the hydrogen storage alloy La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5, according to the original XRD data of FIG. 4-1 (Example D28);

FIG. 4-3 is a pressure-composition-temperature (P-c-T) curve of the alloy LaY₂Ni_9.5Mn_0.5Al_0.3Cu_0.2(Example D38);

FIG. 5-1 is an XRD pattern of the hydrogen storage alloy La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5Zr_0.1Ti_0.1(Example E18);

FIG. 5-2 an redrawn XRD pattern of the hydrogen storage alloy, La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5Zr_0.1Ti_0.1, according to the original XRD data of FIG. 5-1 (Example E18);

FIG. 6-1 is an X ray diffraction pattern of the alloy LaY₂Ni_10.6Mn_0.5Al_0.3Zr_0.1(Example F35);

FIG. 7-1 is an XRD pattern of the hydrogen storage alloy, LaY₂Ni_8.3Mn_0.5Al_0.2Zr_0.1(Example G18);

FIG. 7-2 a redrawn XRD pattern of the hydrogen storage alloy, LaY₂Ni_8.3Mn_0.5Al_0.2Zr_0.1, according to the original XRD data of FIG. 7-1 (Example G18).

DETAILED DESCRIPTION OF THE EMBODIMENT

The embodiments of the invention are further described with reference to the examples and drawings. The examples and the descriptions thereof are to illustrate the invention, yet not to limit the invention.

In the following examples:

1. phase structure analyses are performed on X-Ray Diffractometer (XRD), with the following test condition: Cu target, Ka radiation, tube voltage 40 kV, tube current 100 mA, scanning angle 2θ: 20˜80°, scanning speed: 3°/min and scanning step: 0.02°.

2. Equipments for measuring hydrogen storage amount include a PCT measuring instrument for hydrogen storage alloy, a thermostatic water bath and an analytical balance. The purity of the hydrogen used in the test is 99.999%.

Measuring procedure includes: crushing the alloy plates, sieving the crushed alloy with a 14 mesh (1200 μm) screen and a 200 mesh (74 μm) screen, collecting about 2.5 g of the alloy powder passing through 200 mesh screen and putting it into a sample container, vacuuming the sample container for 5 min, then charging the container with hydrogen, calibrating the volume of the sample container according to the ideal-gas equation, then vacuuming the sample container for 30 min, keeping the pressure below 0.001 MPa, activating the alloy for 3 times at 353K, then vacuuming the sample container for 2 h, and obtaining a pressure-composition-temperature (PCT) curve at 313K.

3. The rare earth based hydrogen storage alloy is produced by high temperature smelting-rapidly quenching method, the method comprising the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching is 3.4 m/s. The copper roller is cooled with cooling water having a temperature of 25° C.

4. The electrochemical parameters involved in the following examples include: N, denoting the number of cycles; C_max, denoting the maximum discharge capacity; S₁₀₀, denoting the capacity retention ratio after 100 cycles; HRD₃₅₀, reflecting the discharge ability under a discharge current density (I_d) of 350 mA·g⁻¹, LTD₂₄₃, denoting the capacity retention ratio at a temperature of 243K; SD₇₂, denoting the capacity retention ratio after the battery being stored for 72 hours (self discharge feature).

High-rate discharge capacity (HRD₃₅₀) mainly reflects the dynamics performance of the hydrogen storage electrodes. HRD₃₅₀is calculated according to the following formula:

$HRD = \frac{C_{d}}{C_{d} + C_{60}} \times 100 %$

wherein: C_ddenotes the discharge capacity measured at a discharge current density (I_d) and a cut-off discharge voltage of 1.0V (vs. Ni(OH)₂/NiOOH counter electrode), C₆₀denotes the residual discharge capacity measured at a discharge current density of I=60 mA·g⁻¹and a cut-off voltage of 1.0V after the alloy electrode has been fully discharge at high discharge current density (I_d). HRD₃₅₀denotes the HRD measured at a discharge current density (I_d) of 350 mA·g⁻¹.

LTD₂₄₃reflects the discharge performance at a low temperature of 243K. The low temperature discharge performance (LTD) is calculated according to the following formula:

$LTD = \frac{C_{T}}{C_{298}} \times 100 %$

In the formula: C_Tdenotes the maximum discharge capacity at a current density of 70 mA/g at a low temperature (243K), C₂₉₈denotes the maximum discharge capacity at a current density of 70 mA/g at the normal temperature (298K).

SD₇₂denotes the self-discharge rate measured after the battery has been rested for 72 hours. SD₇₂reflects the self-discharge ability (charge retention ability). The test condition includes: measuring the discharge capacity C_aby charging a battery for 6 h at a rate of 0.2C, resting the battery for 10 min, discharging the battery to 1.0V at a rate of 0.2C, and then measuring the discharge capacity C_b, by charging the battery at a rate of 0.2C for 6 h, resting the battery for 72 h, discharging the battery to 1.0 V at a rate of 0.2C, and then measuring the discharge capacity C_cby charging and discharging the battery at a rate of 0.2C. SD₇₂, which denotes the charge retention ratio after the battery being rested for 72 h, is calculated by the following formula:
2C_b/(C_a+C_c)×100%

Example A1˜A23

A₂B₇type RE_xY_yNi_z-a-bMn_aAl_bhydrogen storage alloys in Example A1˜A23 were produced by applying the high temperature smelting-rapidly quenching method.

The alloys in Example A13 and Example A14 were produced by using the same raw material composition. The alloy in Example A13 was produced by applying the above-mentioned high temperature smelting-rapidly quenching method, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy in Example A14 was also produced by applying the above-mentioned high temperature smelting-rapidly quenching method. Besides, an annealing step was added to the producing method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example A20 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The test method for electrodes includes: mechanically crushing the alloys of Example A1˜A23 into 200-300 mesh alloy powder, mixing the alloy powder with carbonyl nickel powder by a weight ratio of 1:4, tabletting the mixed powder with a pressure of 16 MPa to form φ15 mm a MH electrodes plate, placing an electrode plate between two pieces of nickel foams, meanwhile, placing nickel belts between the nickel foams as the battery tabs, pressing the nickel forms with a pressure of 16 MPa to form a hydrogen storage anode (MH electrode) for testing, spot welding the edge of the electrode to make sure the electrode and the nickel forms were in close contact.

An open two-electrode system was used to test the electrochemical performance, native electrode was MH electrode; positive electrode was sintered Ni(OH)₂/NiOOH electrode with surplus capacity; electrolyte was 6 mol·L⁻¹KOH solution. The assembled battery was being rested for 24 h, and then tested on a LAND battery testing equipment employing galvanostatic method to test their electrochemical performance (such as activating times, maximum capacity, high rate discharge capacity HRD, cycling stability, etc.). The environmental temperature during the test is 298K. The charge current density was 70 mA·g⁻¹; the charging time was 6 h; the discharge current density was 70 mA·g⁻¹; the discharge cut-off voltage was 1.0V, the interval between each charge and discharge was 10 min.

The A₂B₇type RE_xY_yNi_z-a-bMn_aAl_bhydrogen storage alloys of Example A1˜A23 and their electrochemical performance are listed in Table 1.

TABLE 1 A₂B₇type RE_xY_yNi_z−a−bMn_aAl_bhydrogen storage alloy and their electrochemical performance electrochemical performances C_max S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ A1 LaY₂Ni_8.7Mn_0.5Al_0.3 3 381 95 93 81 80 A2 LaY₂Ni_9.7Mn_0.5Al_0.3 2 386 93 91 82 83 A3 LaY₂Ni₁₀Mn_0.5Al_0.3 2 375 93 91 86 84 A4 LaY₂Ni₁₀Mn_0.5 2 378 93 93 82 81 A5 LaY₂Ni_9.5Mn 1 367 91 90 85 82 A6 La_0.5Y_2.5Ni_9.5Mn 1 352 95 92 87 81 A7 La_0.5Y_2.5Ni_9.5Al 3 337 98 87 85 86 A8 La₂YNi_9.5Mn 3 365 88 89 82 85 A9 La_2.5Y_0.5Ni_9.5Mn 3 351 85 85 79 87 A10 LaY₂Ni₁₀Al_0.5 3 346 98 91 85 83 A11 LaY₂Ni_9.3MnAl_0.2 1 352 93 90 86 83 A12 LaY₂Ni₉MnAl_0.5 2 349 96 87 83 85 A13 LaY₂Ni_9.5Mn_0.5Al_0.5 2 362 90 89 84 80 A14 LaY₂Ni_9.5Mn_0.5Al_0.5 3 369 92 91 86 83 A15 LaY_1.5Ce_0.5Ni_9.5Mn_0.5Al_0.5 3 357 93 88 81 83 A16 LaY_1.5Sm_0.5Ni_9.5Mn_0.5Al_0.5 3 343 95 91 86 85 A17 La_0.8Ce_0.2Y₂Ni_9.5Mn_0.5Al_0.5 3 363 93 90 85 80 A18 La_0.8Ce_0.2Y_1.5Sm_0.5Ni_9.5Mn_0.5Al_0.5 3 354 96 84 83 80 A19 La_0.8Ce_0.2Y_1.5Nd_0.5Ni_9.5Mn_0.5Al_0.5 3 352 97 82 83 81 A20 MlY₂Ni_9.5Mn_0.5Al_0.5 3 352 96 90 85 83 A21 La_0.8Ce_0.2Y₂Ni_8.5Mn_1.5Al_0.5 3 353 92 88 86 82 A22 La_0.8Ce_0.2Y₂Ni_7.5Mn_2.5Al_0.5 3 342 93 82 87 85 A23 LaCe_0.5Y_1.5Ni_9.7Mn_0.5Al_0.3 3 361 90 85 87 86

According to Table 1, compared with the LaY₂Ni_9.5Mn_0.5Al_0.5alloy of Example A13, the alloy electrode of Example A14, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaCe_0.5Y_1.5Ni_9.7Mn_0.5Al_0.3alloy of Example A23 was analyzed by an X-ray diffractometer. FIG. 1-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 1-1, the alloy may contains Ce₂Ni₇phase, Y₂Ni₇phase, LaNi₅phase, LaY₂Ni₉phase or La_0.5Ce_0.5Y₂Ni₉phase.

FIG. 1-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example A23. As shown in the figure, the alloy contains Y₂Ni₇phase, La₂Ni₇phase, LaNi₅phase and Ce₂Ni₇phase.

FIG. 1-3 is a pressure-composition-temperature curve (P-c-T curve) of LaY₂Ni_9.5Mn_0.5Al_0.5alloy of Example A13 measured at 313K by applying Sievert method. As shown in FIG. 1-3, the maximum hydrogen storage capacity of the alloy could reach 1.36 wt % and the hydrogen desorption plateau pressure is about 0.05 MPa. The A31212482001 curve denotes the hydrogen absorption curve of the alloy and the D31212482001 curve denotes the hydrogen desorption curve of the alloy.

Example B1˜B22

The A₅B₁₉type RE_xY_yNi_z-a-bMn_aAl_bof Example B1˜B22 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example B13 and Example B14 were prepared from the same raw materials. The alloy of Example B13 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example B14 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example B20 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The A₅B₁₉type RE_xY_yNi_z-a-bMn_aAl_bhydrogen storage alloys of Example B1˜B22 and their electrochemical performance are listed in the following table.

TABLE 2 A₅B₁₉type RE_xY_yNi_z−a−bMn_aAl_bhydrogen storage alloy and their electrochemical performance electrochemical performances C_max S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ B1 LaY₂Ni_10.2Mn_0.5Al_0.3 3 372 93 95 80 83 B2 LaY₂Ni_10.6Mn_0.5Al_0.3 2 383 90 91 82 81 B3 LaY₂Ni_11.7Mn_0.5Al_0.3 2 365 95 90 83 85 B4 LaY₂Ni_10.6Mn_0.8 2 376 93 93 80 82 B5 LaY₂Ni_9.9Mn_1.5 1 367 91 90 85 81 B6 La_0.5Y_2.5Ni_9.9Mn_1.5 3 351 94 93 87 82 B7 La_2.0YNi_9.9Mn_1.5 2 361 92 89 84 85 B8 La_2.5Y_0.5Ni_9.9Mn_1.5 1 353 89 87 80 87 B9 LaY₂Ni_9.9Al_1.5 3 330 98 88 83 89 B10 LaY₂Ni_10.6Al_0.8 3 342 96 91 87 83 B11 LaY₂Ni_9.4Mn_1.5Al_0.5 1 362 93 90 83 80 B12 LaY₂Ni_10.1MnAl_0.3 2 383 90 87 85 82 B13 LaY₂Ni_9.9MnAl_0.5 2 380 92 89 81 80 B14 LaY₂Ni_9.9MnAl_0.5 3 383 93 91 86 83 B15 LaY_1.5Ce_0.5Ni_9.9MnAl_0.5 3 372 96 88 81 85 B16 LaY_1.5Sm_0.5Ni_9.9MnAl_0.5 3 363 95 90 85 83 B17 La_0.8Ce_0.2Y₂Ni_9.9MnAl_0.5 3 370 93 90 82 80 B18 La_0.8Ce_0.2Y_1.5Sm_0.5Ni_9.9MnAl_0.5 3 354 96 87 85 83 B19 La_0.8Ce_0.2Y_1.5Nd_0.5Ni_9.9MnAl_0.5 3 351 97 87 83 85 B20 MlY₂Ni_9.9MnAl_0.5 3 360 94 90 81 82 B21 La_0.8Ce_0.2Y₂Ni_9.4Mn_1.5Al_0.5 3 362 91 87 85 83 B22 La_0.8Ce_0.2Y₂Ni_7.9Mn₃Al_0.5 3 350 93 82 86 85

According to Table 2, compared with the LaY₂Ni_9.9MnAl_0.5alloy of Example B13, the alloy electrode of Example B14, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni_10.6Mn_0.5Al_0.3alloy (Example B2) was analyzed by an X-ray diffractometer. FIG. 2-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 2-1, the alloy may contain MnNi₈Y₃phase, YNi_3.912Al_1.088phase, LaNi₅phase, Ni₇Y₂phase, or LaY₂Ni₉phase, etc. The alloy may also contain YNi₃phase, Y₂Ni₇phase, LaY₂Ni₉phase, LaNi₅phase, Pr₅Co₁₉phase or Ce₅Co₁₉phase, etc.

FIG. 2-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example B2. As shown in the figure, the alloy contains Y₂Ni₇, La₂Ni₇, LaNi₅and Al₂Ni₆Y₃phase.

FIG. 2-3 is a pressure-composition-temperature curve (P-c-T curve) of LaY₂Ni_10.6Mn_0.5Al_0.3alloy (Example B2) measured at 313K by applying Sievert method. As shown in FIG. 2-3, the maximum hydrogen storage capacity of the alloy could reach 1.33 wt % and the hydrogen desorption plateau pressure is about 0.1 MPa. The A32512333001 curve in denotes the hydrogen absorption curve of the alloy and D32512333001 curve denotes the hydrogen desorption curve of the alloy.

Example C1˜C22

The AB₃type RE_xY_yNi_z-a-bMn_aAl_bhydrogen storage alloy of Example C1˜C22 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example C13 and Example C14 were prepared from the same raw materials. The alloy of Example C13 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example C14 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example C20 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_xY_yNi_z-a-bMn_aAl_bhydrogen storage alloys of Example C1˜C22 and their electrochemical performance are listed in the following table 3.

TABLE 3 RE_xY_yNi_z−a−bMn_aAl_bhydrogen storage alloy and their electrochemical performance electrochemical performances C_max S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ C1 LaY₂Ni_7.7Mn_0.5Al_0.3 2 345 92 89 80 81 C2 LaY₂Ni_8.2Mn_0.5Al_0.3 2 362 93 91 81 83 C3 LaY₂Ni_8.5Mn_0.5Al_0.3 3 369 95 93 82 80 C4 LaY₂Ni_8.5Mn_0.5 2 367 93 93 80 78 C5 LaY₂Ni₈Mn 1 357 91 90 80 82 C6 La_0.5Y_2.5Ni₈Mn 3 351 97 93 85 80 C7 La_2.0YNi₈Mn 2 359 95 89 82 82 C8 La_2.5Y_0.5Ni₈Mn 1 354 91 87 79 85 C9 LaY₂Ni₈Al 3 342 98 87 81 85 C10 LaY₂Ni_8.5Al_0.5 3 339 98 91 81 83 C11 LaY₂Ni_7.7MnAl_0.2 1 342 93 90 83 83 C12 LaY₂Ni_7.5MnAl_0.5 2 332 96 87 81 85 C13 LaY₂Ni₈Mn_0.5Al_0.5 2 352 90 89 80 80 C14 LaY₂Ni₈Mn_0.5Al_0.5 3 362 91 92 83 82 C15 LaY_1.5Ce_0.5Ni₈Mn_0.5Al_0.5 3 345 93 88 82 85 C16 LaY_1.5Sm_0.5Ni₈Mn_0.5Al_0.5 3 335 95 92 80 86 C17 La_0.8Ce_0.2Y₂Ni₈Mn_0.5Al_0.5 3 357 92 90 80 82 C18 La_0.8Ce_0.2Y_1.5Sm_0.5Ni₈Mn_0.5Al_0.5 3 351 97 86 82 86 C19 La_0.8Ce_0.2Y_1.5Nd_0.5Ni₈Mn_0.5Al_0.5 3 348 98 87 82 87 C20 MlY₂Ni₈Mn_0.5Al_0.5 3 352 96 90 81 83 C21 La_0.8Ce_0.2Y₂Ni₇Mn_1.5Al_0.5 3 343 90 87 83 82 C22 La_0.8Ce_0.2Y₂Ni_6.5Mn₂Al_0.5 3 337 92 89 85 86

According to Table 3, compared with the LaY₂Ni₈Mn_0.5Al_0.5alloy of Example C13, the alloy electrode of Example C14, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni₈Mn_0.5Al_0.5alloy (Example C13) was analyzed by an X-ray diffractometer. FIG. 3-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 3-1, the alloy may contain MnNi₈Y₃phase, Al_0.20LaNi_2.80phase or LaMn_0.17Ni_2.83phase, etc. The alloy may also contain YNi₃phase or LaNi₃phase, etc.

FIG. 3-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example C13. As shown in the figure, the alloy contains LaY₂Ni₉phase or Ni₇Y₂phase.

Example D1˜D38

The RE_xY_yNi_z-a-b-cMn_aAl_bM_chydrogen storage alloy of Example D1˜D38 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example D7 and D8 as well as Example D28 and D29 were prepared from the same raw materials. The alloy of Example D7 and D28 were prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example D8 and D29 were prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example D37 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_xY_yNi_z-a-b-cMn_aAl_bM_chydrogen storage alloys of Example D1˜D38 and their electrochemical performance are listed in the following table.

TABLE 4 RE_xY_yNi_{z−a−b−c}Mn_aAl_bM_chydrogen storage alloy and their electrochemical performance electrochemical performances C_max S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ D1 LaY₂Ni_6.5MnAl_0.5Cu 3 352 95 93 81 83 D2 LaY₂Ni_6.5MnAl_0.5Fe 2 346 94 93 82 81 D3 LaY₂Ni_6.5MnAl_0.5Co 2 368 92 90 81 83 D4 LaY₂Ni_6.5MnAl_0.5Sn 2 356 93 92 80 80 D5 LaY₂Ni_6.5MnAl_0.5(VFe) 1 347 95 87 82 81 D6 LaY₂Ni_6.5MnAl_0.5W 3 352 93 90 78 80 D7 LaY₂Ni₈MnAl_0.5Cu 3 371 90 88 81 80 D8 LaY₂Ni₈MnAl_0.5Cu 2 376 92 91 83 82 D9 La_0.5Y_2.5Ni₈MnAl_0.5Cu 3 362 96 93 84 80 D10 La₂YNi₈MnAl_0.5Cu 2 367 90 87 80 82 D11 La_2.5Y_0.5Ni₈MnAl_0.5Cu 1 360 87 85 77 83 D12 LaY₂Ni₈MnAlCu 3 355 95 83 82 85 D13 LaY₂Ni₈MnAlCu_0.1 3 361 92 82 79 87 D14 LaY₂Ni₈MnAl_0.5Fe 2 363 93 90 81 81 D15 LaY₂Ni₈MnAl_0.5Co 2 378 90 92 83 82 D16 LaY₂Ni₈MnAl_0.5Sn 2 362 95 92 82 79 D17 LaY₂Ni₈MnAl_0.5(VFe) 1 357 93 90 82 81 D18 LaY₂Ni₈MnAl_0.5W 3 352 97 91 83 80 D19 LaY₂Ni_9.9MnAl_0.5Cu 3 365 91 90 81 82 D20 LaY₂Ni_9.9MnAl_0.5Fe 2 353 94 91 80 79 D21 LaY₂Ni_9.9MnAl_0.5Co 2 369 95 90 81 80 D22 LaY₂Ni_9.9MnAl_0.5Sn 2 356 96 92 78 82 D23 LaY₂Ni_9.9MnAl_0.5(VFe) 1 347 93 90 82 81 D24 LaY₂Ni_9.9MnAl_0.5W 3 342 98 91 84 83 D25 LaY₂Ni₉MnAl_0.5CoCu 3 352 95 93 85 83 D26 LaY₂Ni₅MnAl_0.5CuSn 2 349 96 91 82 81 D27 LaY₂Ni₈MnAl_0.5CoCuSn_0.5 2 354 95 90 78 80 D28 La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5 2 372 90 89 81 79 D29 La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5 3 377 92 91 84 82 D30 LaY₂Ni_8.9MnAl_0.5(VFe) 1 352 93 91 82 81 D31 LaY₂Ni_8.9MnAl_0.5W 3 339 98 91 85 83 D32 LaY_1.5Ce_0.5Ni₈MnAl_0.5Cu 3 363 92 89 83 82 D33 LaY_1.5Sm_0.5Ni₈MnAl_0.5Co 3 353 95 90 85 83 D34 La_0.8Ce_0.2Y₂Ni₈MnAl_0.5Fe 3 356 93 90 82 80 D35 La_0.8Ce_0.2Y_1.5Sm_0.5Ni₈MnAl_0.5Sn 3 334 97 90 85 83 D36 La_0.8Ce_0.2Y_1.5Nd_0.5Ni₈MnAl_0.5Sn 3 331 97 91 84 84 D37 MlY₂Ni_7.7MnAl_0.3CoCu_0.5 3 355 92 90 83 82 D38 LaY₂Ni_9.5Mn_0.5Al_0.3Cu_0.2 2 363 92 88 81 80

According to Table 4, compared with the alloys of Example D7 and D28 respectively, the alloy electrodes of Example D8 and D29, which have been subjected to annealing heat treatment, have increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5alloy (Example D28) was analyzed by an X-ray diffractometer. FIG. 4-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 4-1, the alloy may mainly contain La₂Ni₇phase.

FIG. 4-2 shows a redrawn XRD pattern of hydrogen storage alloy La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5according to the original XRD data of Example D28. As shown in the figure, the alloy contains Y₂Ni₇phase, La₂Ni₇phase or Ni₅Y phase.

FIG. 4-3 is a pressure-composition-temperature curve (P-c-T curve) of LaY₂Ni_9.5Mn_0.5Al_0.3Cu_0.2alloy (Example D38) measured at 313K by applying Sievert method. As shown in FIG. 4-3, the maximum hydrogen storage capacity of the alloy could reach 1.28 wt % and the hydrogen desorption plateau pressure is about 0.03 MPa. The A32513142001 curve in denotes the hydrogen absorption curve of the alloy and D32513142001 curve denotes the hydrogen desorption curve of the alloy.

Example E1˜E34

The RE_xY_yNi_z-a-b-cMn_aAl_bM_cZr_ATi_Bhydrogen storage alloy of Example E1˜E34 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example E14 and Example E15 were prepared from the same raw materials. The alloy of Example E14 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example E15 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example E28 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_xY_yNi_z-a-b-cMn_aAl_bM_cZr_ATi_Bhydrogen storage alloys of Example E1˜E34 and their electrochemical performance are listed in the following table.

TABLE 5 RE_xY_yNi_{z−a−b−c}Mn_aAl_bM_cZr_ATi_Bhydrogen storage alloy and their electrochemical performance electrochemical performances S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N C_maxmAh · g⁻¹ (%) (%) (%) SD₇₂ E1 LaY₂Ni_8.7Mn_0.5Al_0.3Zr_0.5Ti_0.3 3 386 96 92 79 82 E2 LaY₂Ni_9.7Mn_0.5Al_0.3Zr_0.5Ti_0.3 2 389 94 92 82 83 E3 LaY₂Ni₁₀Mn_0.5Al_0.3Zr_0.3Ti_0.2 2 382 93 91 80 81 E4 LaY₂Ni₁₀Mn_0.5Zr_0.5Ti_0.3 2 387 91 90 82 79 E5 La_0.5Y_2.5Ni₁₀Mn_0.5Zr_0.5Ti_0.3 3 373 95 93 84 82 E6 La₂YNi₁₀Mn_0.5Zr_0.5Ti_0.3 2 379 92 91 81 80 E7 La_2.5Y_0.5Ni₁₀Mn_0.5Zr_0.5Ti_0.3 1 381 89 87 78 81 E8 LaY₂Ni_9.5MnZr_0.5Ti_0.3 1 373 92 90 83 81 E9 LaY₂Ni₉Mn_1.5Zr_0.5Ti_0.3 2 365 91 87 79 83 E10 LaY₂Ni_8.5Mn₂Zr_0.5Ti_0.3 3 359 89 85 75 84 E11 LaY₂Ni₁₀Al_0.5Zr_0.5Ti_0.3 3 352 96 90 79 82 E12 LaY₂Ni_9.2MnAl_0.3Zr_0.5Ti_0.3 1 360 92 89 81 80 E13 LaY₂Ni₉MnAl_0.5Zr_0.5Ti_0.3 2 354 94 89 82 83 E14 LaY₂Ni_9.5Mn_0.5Al_0.5Zr_0.5Ti_0.3 2 367 92 90 79 80 E15 LaY₂Ni_9.5Mn_0.5Al_0.5Zr_0.5Ti_0.3 3 375 93 92 83 83 E16 LaY₂Ni₉Mn_0.5AlZr_0.5Ti_0.3 3 366 97 90 80 85 E17 La_1.2Y_1.8Ni_9.6Mn_0.5Al_0.3Co_0.1Zr_0.1Ti_0.1 2 378 91 93 80 77 E18 La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5Zr_0.1Ti_0.1 3 371 93 91 79 80 E19 La_1.2Y_1.8Ni_8.7Mn_0.5Al_0.3CoZr_0.1Ti_0.1 3 362 95 88 76 82 E20 La_1.2Y_1.8Ni_7.7Mn_0.5Al_0.3Co₂Zr_0.1Ti_0.1 4 351 98 85 72 85 E21 LaY_1.5Ce_0.5Ni_9.5Mn_0.5Al_0.5Zr_0.5 3 363 95 90 82 85 E22 LaY_1.5Ce_0.5Ni_9.5Mn_0.5Al_0.5Zr 5 342 98 87 80 86 E23 LaY_1.5Sm_0.5Ni_9.5Mn_0.5Al_0.5Ti_0.5 3 349 93 91 80 82 E24 LaY_1.5Sm_0.5Ni_9.5Mn_0.5Al_0.5Ti 4 337 97 89 81 85 E25 La_0.8Ce_0.2Y₂Ni_9.5Mn_0.5Al_0.5Zr_0.3Ti_0.2 3 370 95 91 82 81 E26 La_0.8Ce_0.2Y_1.5Sm_0.5Ni_9.5Mn_0.5Al_0.5Zr_0.2 3 362 95 88 78 79 E27 La_0.8Ce_0.2Y_1.5Nd_0.5Ni_9.5Mn_0.5Al_0.5Zr_0.2 3 359 96 90 80 81 E28 MlY₂Ni_9.5Mn_0.5Al_0.5Ti_0.2 3 357 93 91 80 81 E29 LaY₂Ni_9.3Mn_0.5Al_0.2Cu_0.5Zr_0.3Ti_0.2 3 374 92 92 81 82 E30 LaY₂Ni_9.3Mn_0.5Al_0.2Fe_0.5Zr_0.5 2 369 95 91 83 82 E31 LaY₂Ni_9.3Mn_0.5Al_0.2Co_0.5Zr_0.3Ti_0.2 2 387 93 90 83 81 E32 LaY₂Ni_9.3Mn_0.5Al_0.2Sn_0.5Ti_0.3 2 366 93 92 82 80 E33 LaY₂Ni_9.3Mn_0.5Al_0.2(VFe)_0.5Zr_0.3 2 361 95 91 80 81 E34 LaY₂Ni_9.3Mn_0.5Al_0.2W_0.5Zr_0.3 3 355 96 90 82 80

According to Table 5, compared with the LaY₂Ni_9.5Mn_0.5Al_0.5Zr_0.5Ti_0.3alloy of Example E14, the alloy electrode of Example E15, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the La_1.2Y_1.8Ni_9.2Mn_0.5Al_0.3Co_0.5Zr_0.1Ti_0.1alloy (Example E18) was analyzed by an X-ray diffractometer. FIG. 5-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 5-1, the alloy may contain La₂Ni₇phase, LaY₂Ni₉phase, Y₂Ni₇phase, Ni₅La phase or LaNi₅phase, etc. The alloy may also contain Ce₂Ni₇or Y₂Ni₇phase.

FIG. 5-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example E18. As shown in the figure, the alloy contains Y₂Ni₇, La₂Ni₇, Ni₅Y phase.

Example F1˜F35

The RE_xY_yNi_z-a-b-cMn_aAl_bM_cZr_ATi_Bhydrogen storage alloy of Example F1˜B35 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example F12 and Example F13 were prepared from the same raw materials. The alloy of Example F12 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount) wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example F13 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example F24 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_xY_yNi_z-a-b-cMn_aAl_bM_cZr_ATi_Bhydrogen storage alloys of Example F1˜F35 and their electrochemical performance are listed in the following table 6.

TABLE 6 RE_xY_yNi_{z−a−b−c}Mn_aAl_bM_cZr_ATi_Bhydrogen storage alloy and their electrochemical performance electrochemical performances S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N C_maxmAh · g⁻¹ (%) (%) (%) SD₇₂ F1 LaY₂Ni_10.2Mn_0.5Al_0.3Zr_0.5Ti_0.3 3 377 95 92 83 80 F2 LaY₂Ni_10.6Mn_0.5Al_0.3Zr_0.5Ti_0.3 2 387 93 90 82 81 F3 LaY₂Ni_11.7Mn_0.5Al_0.3Zi_0.3Ti_0.2 2 371 95 91 80 85 F4 LaY₂Ni_10.6Mn_0.8Zr_0.5Ti_0.3 2 380 94 92 82 82 F5 La_0.5Y_2.5Ni_10.6Mn_0.8Zr_0.5Ti_0.3 3 374 96 93 85 77 F6 La₂YNi_10.6Mn_0.8Zr_0.5Ti_0.3 2 383 89 90 81 83 F7 La_2.5Y_0.5Ni_10.6Mn_0.8Zr_0.5Ti_0.3 1 377 88 87 78 85 F8 LaY₂Ni_9.9Mn_1.5Zr_0.5Ti_0.3 1 375 93 91 85 82 F9 LaY₂Ni_10.6Al_0.8Zr_0.5Ti_0.3 3 353 98 92 85 83 F10 LaY₂Ni_9.4Mn_1.5Al_0.5Zr_0.5Ti_0.3 1 369 95 91 83 83 F11 LaY₂Ni_10.1MnAl_0.3Zr_0.5Ti_0.3 2 388 93 89 85 82 F12 LaY₂Ni_9.9MnAl_0.5Zr_0.5Ti_0.3 2 385 92 91 83 82 F13 LaY₂Ni_9.9MnAl_0.5Zr_0.5Ti_0.3 3 387 93 93 85 83 F14 LaY₂Ni_8.9Mn₂Al_0.5Zr_0.5Ti_0.3 2 375 92 90 82 85 F15 LaY₂Ni_8.4Mn_2.5Al_0.5Zr_0.5Ti_0.3 2 371 91 88 81 86 F16 LaY₂Ni_9.9MnAl_0.5ZrTi_0.3 4 357 98 92 86 87 F17 LaY_1.5Ce_0.5Ni_9.9MnAl_0.5Zr_0.5 3 380 95 90 83 82 F18 LaY_1.5Sm_0.5Ni_9.9MnAl_0.5Ti_0.5 3 365 94 90 82 81 F19 LaY_1.5Sm_0.5Ni_9.9MnAl_0.5Ti 4 357 96 91 83 79 F20 La_0.8Ce_0.2Y₂Ni_9.9MnAl_0.5Zr_0.3Ti_0.2 3 378 92 90 85 83 F21 La_0.8Ce_0.2Y₂Ni_9.4MnAlZr_0.3Ti_0.2 4 361 97 83 80 85 F22 La_0.8Ce_0.2Y_1.5Sm_0.5Ni_9.9MnAl_0.5Zr_0.2 3 357 96 89 84 80 F23 La_0.8Ce_0.2Y_1.5Nd_0.5Ni_9.9MnAl_0.5Zr_0.2 3 358 96 90 85 82 F24 MlY₂Ni_9.9MnAl_0.5Ti_0.2 3 363 96 91 82 82 F25 LaY₂Ni_10.2Mn_0.5Al_0.2Cu_0.5Zr_0.3Ti_0.2 3 370 93 90 82 80 F26 LaY₂Ni_10.2Mn_0.5Al_0.2Fe_0.5Zr_0.5 2 358 96 90 83 81 F27 LaY₂Ni_10.6Mn_0.5Al_0.2Co_0.1Zr_0.3Ti_0.2 1 377 92 93 84 78 F28 LaY₂Ni_10.2Mn_0.5Al_0.2Co_0.5Zr_0.3Ti_0.2 2 374 95 91 82 80 F29 LaY₂Ni_9.7Mn_0.5Al_0.2CoZr_0.3Ti_0.2 3 362 96 88 79 82 F30 LaY₂Ni_8.7Mn_0.5Al_0.2Co₂Zr_0.3Ti_0.2 4 351 97 85 75 83 F31 LaY₂Ni_8.2Mn_0.5Al_0.2Co_2.5Zr_0.3Ti_0.2 4 342 98 81 71 85 F32 LaY₂Ni_10.2Mn_0.5Al_0.2Sn_0.5Ti_0.3 2 361 95 90 81 79 F33 LaY₂Ni_10.2Mn_0.5Al_0.2(VFe)_0.5Zr_0.3 1 356 95 91 83 82 F34 LaY₂Ni_10.2Mn_0.5Al_0.2W_0.5Zr_0.3 3 350 98 92 84 83 F35 LaY₂Ni_10.6Mn_0.5Al_0.3Zr_0.1 1 377 93 93 85 83

According to Table 6, compared with the LaY₂Ni_9.9MnAl_0.5Zr_0.5Ti_0.3alloy of Example F12, the alloy electrode of Example F13, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni_10.6Mn_0.5Al_0.3Zr_0.1alloy (Example F35) was analyzed by an X-ray diffractometer. FIG. 6-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 6-1, the alloy may contain Y₂Ni₇phase, La₂Ni₇phase, Pr₅Co₁₉phase, Ce₅Co₁₉phase or LaNi₅phase.

Example G1˜G34

The RE_xY_yNi_z-a-b-cMn_aAl_bM_cZr_ATi_Bhydrogen storage alloy of Example G1˜G34 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example G15 and Example G16 were prepared from the same raw materials. The alloy of Example G15 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example G16 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount) wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example G25 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_xY_yNi_z-a-b-cMn_aAl_bM_cZr_ATi_Bhydrogen storage alloys of Example G1˜G34 and their electrochemical performance are listed in the following table.

TABLE 7 RE_xY_yNi_{z−a−b−c}Mn_aAl_bM_cZr_ATi_Bhydrogen storage alloy and their electrochemical performance electrochemical performances S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N C_maxmAh · g⁻¹ (%) (%) (%) SD₇₂ G1 LaY₂Ni_7.7Mn_0.5Al_0.3Zr_0.5Ti_0.3 2 353 96 91 80 80 G2 LaY₂Ni_8.2Mn_0.5Al_0.3Zr_0.5Ti_0.3 2 367 93 90 79 81 G3 LaY₂Ni_8.5Mn_0.5Al_0.3Zr_0.3Ti_0.2 3 375 92 91 77 80 G4 La_0.5Y_2.5Ni_8.5Mn_0.5Al_0.3Zr_0.3Ti_0.2 4 351 97 94 81 76 G5 La₂YNi_8.5Mn_0.5Al_0.3Zr_0.3Ti_0.2 2 363 93 89 75 79 G6 LaY₂Ni_8.9Mn_0.5Zr_0.1Ti_0.3 1 374 90 92 81 77 G7 LaY₂Ni_8.5Mn_0.5Zr_0.5Ti_0.3 2 372 93 92 78 79 G8 LaY₂Ni₈Mn_0.5ZrTi_0.3 3 365 97 87 73 81 G9 LaY₂Ni₈MnZr_0.5Ti_0.3 1 363 91 90 77 80 G10 LaY₂Ni_7.5Mn_1.5Zr_0.5Ti_0.3 2 359 90 87 74 83 G11 LaY₂Ni₇Mn₂Zr_0.5Ti_0.3 3 350 93 85 71 85 G12 LaY₂Ni_8.5Al_0.5Zr_0.5Ti_0.1 3 343 98 92 80 83 G13 LaY₂Ni_7.7MnAl_0.3Zr_0.5Ti_0.3 1 352 92 89 78 81 G14 LaY₂Ni_7.5MnAl_0.5Zr_0.5Ti_0.3 2 340 97 90 81 82 G15 LaY₂Ni₈Mn_0.5Al_0.5Zr_0.5Ti_0.3 2 359 91 89 79 82 G16 LaY₂Ni₈Mn_0.5Al_0.5Zr_0.5Ti_0.3 3 370 92 91 80 82 G17 LaY₂Ni_7.5Mn_0.5AlZr_0.5Ti_0.3 4 352 96 88 75 84 G18 LaY₂Ni_8.3Mn_0.5Al_0.2Zr_0.1 3 367 93 90 79 80 G19 LaY_1.5Ce_0.5Ni₈Mn_0.5Al_0.5Zr_0.5 3 351 94 89 77 80 G20 LaY_1.5Sm_0.5Ni₈Mn_0.5Al_0.5Ti_0.5 2 357 93 91 76 83 G21 LaY_1.5Sm_0.5Ni₈Mn_0.5Al_0.5Ti 3 348 96 93 80 82 G22 La_0.8Ce_0.2Y₂Ni₈Mn_0.5Al_0.5Zr_0.3Ti_0.2 3 368 92 91 79 80 G23 La_0.8Ce_0.2Y_1.5Sm_0.5Ni₈Mn_0.5Al_0.5Zr_0.2 3 355 95 88 80 79 G24 La_0.8Ce_0.2Y_1.5Nd_0.5Ni₈Mn_0.5Al_0.5Zr_0.2 3 352 96 90 81 80 G25 MlY₂Ni₈Mn_0.5Al_0.5Ti_0.2 3 359 96 91 78 80 G26 LaY₂Ni_7.8Mn_0.5Al_0.2Cu_0.5Zr_0.3Ti_0.2 3 363 93 94 82 81 G27 LaY₂Ni_7.8Mn_0.5Al_0.2Fe_0.5Zr_0.5 2 352 93 92 83 81 G28 LaY₂Ni_8.2Mn_0.5Al_0.2Co_0.1Zr_0.3Ti_0.2 2 375 90 89 84 80 G29 LaY₂Ni_7.8Mn_0.5Al_0.2Co_0.5Zr_0.3Ti_0.2 2 373 93 91 81 82 G30 LaY₂Ni_7.3Mn_0.5Al_0.2CoZr_0.3Ti_0.2 3 361 96 87 77 83 G31 LaY₂Ni_6.3Mn_0.5Al_0.2Co₂Zr_0.3Ti_0.2 4 348 98 82 73 85 G32 LaY₂Ni_7.8Mn_0.5Al_0.2Sn_0.5Ti_0.3 2 359 94 92 80 79 G33 LaY₂Ni_7.8Mn_0.5Al_0.2(VFe)_0.5Zr_0.3 1 352 96 89 82 80 G34 LaY₂Ni_7.8Mn_0.5Al_0.2W_0.5Zr_0.3 3 355 95 91 82 81

According to Table 7, compared with the LaY₂Ni₈Mn_0.5Al_0.5Zr_0.5Ti_0.3alloy of Example G15, the alloy electrode alloy of Example G16, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni_8.3Mn_0.5Al_0.2Zr_0.1alloy (Example G18) was analyzed by an X-ray diffractometer. FIG. 7-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 7-1, the alloy may contain LaY₂Ni₉phase or LaNi phase.

FIG. 7-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example G18. As shown in the figure, the alloy contain LaY₂Ni₉phase.

Finally, it should be noted that the above embodiments are merely provided for describing the technical solutions of the present invention but not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those of ordinary skill in the art: the technical features of the present invention may still be modified or equivalent replacements may be made to some technical features; without departing from the spirit of the present invention, which should be covered in the scope of the technical solutions.

Claims

1. A rare earth based hydrogen storage alloy represented by the general formula (I):

RExYyNiz-a-b-cMnaAlbMcZrATiB (I)

wherein RE denotes one or more element(s) selected from the group consisting of La, Ce, Pr, Nd, Sm, and Gd; M denotes one or more element(s) selected from the group consisting of Cu, Fe, Co, Sn, V, and W; x>0, y≥0.5, and x+y=3, 13≥z≥7; 6≥a+b>0, 5≥c≥0, and 4≥A+B≥0.

2. The rare earth based hydrogen storage alloy according to claim 1, wherein x>0, y≥0.5, x+y=3; 12.5≥z≥8.5; 5.5≥a+b>0, 3.5≥c≥0, and 2.5≥A+B≥0.

3. The rare earth based hydrogen storage alloy according to claim 2, wherein c=0 and A=B=0.

4. The rare earth based hydrogen storage alloy according to claim 3, wherein 12.5≥z≥11.

5. The rare earth based hydrogen storage alloy according to claim 3, wherein 11>z≥9.5; and 4.5≥a+b>0.

6. The rare earth based hydrogen storage alloy according to claim 3, wherein 9.5>z≥8.5; and 3.5≥a+b>0.

7. The rare earth based hydrogen storage alloy according to claim 2, wherein A=B=0, and c>0.

8. The rare earth based hydrogen storage alloy according to claim 7, wherein 3.5≥a+b≥0; and 3.0≥c>0.

9. The rare earth based hydrogen storage alloy according to claim 2, wherein 2.5≥A+B>0.

10. The rare earth based hydrogen storage alloy according to claim 9, wherein 12.5≥z≥11, and 4≥a+b>0.

11. The rare earth based hydrogen storage alloy according to claim 9, wherein 11>z≥9.5; 3.5≥a+b>0; and 3≥c≥0.

12. The rare earth based hydrogen storage alloy according to claim 9, wherein 9.5>z≥8.5; 3≥a+b>0; and 2.5≥c≥0.

13. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iv) apply:

i) 2.0≥x≥0.5;

ii) 3.0≥a≥0.5;

iii) 1.5≥b≥0.3;

iv) z=11.4.

14. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iv) apply:

i) 2.0≥x≥0.5;

ii) 2.5≥a≥0.5;

iii) 1.0≥b≥0.2;

iv) z=10.5.

15. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iv) apply:

i) 2.0≥x≥0.5;

ii) 2.0≥a≥0.5;

iii) 1.0≥b≥0.2;

iv) z=9.

16. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-v) apply:

i) 2.0≥x≥0.5;

ii) 2.0≥a≥0.5;

iii) 1.0≥b≥0.3;

iv) 11.4≥z≥9;

v) 2.5≥c≥0.1.

17. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-vii) apply:

i) 2≥x≥0.5;

ii) 2.5≥a≥0.5;

iii) 1.0≥b≥0.2;

iv) z=11.4;

v) 2.5≥c≥0.1;

vi) 1.0≥A≥0.1;

vii) 1.0≥B≥0.1.

18. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-vii) apply:

i) 2.0≥x≥0.5;

ii) 2.0≥a≥0.5;

iii) 1.0≥b≥0.2;

iv) z=10.5;

v) 2.0≥c≥0.1;

vi) 1.0≥A≥0.1;

vii) 1.0≥B≥0.1.

19. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-vii) apply:

i) 2.0≥x≥0.5;

ii) 2.0≥a≥0.5;

iii) 1.0≥b≥0.2;

iv) z=9;

v) 2.0≥c≥0.1;

vi) 1.0≥A≥0.1;

vii) 1.0≥B≥0.1.

20. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iii) apply:

i) the alloy has a maximum hydrogen storage capacity of 1.2-1.5 wt % at 313K;

ii) when utilized as a negative material electrode for a Ni-MH battery, the alloy has a maximum discharge capacity of 300-400 mAh/g at a current density of 70 mA/g;

iii) the alloy has a capacity retention of more than 85%, at a current density of 70 mA/g.

21. A hydrogen storage medium comprising the rare earth based hydrogen storage alloy according to claim 1.

22. An electrode of a secondary battery comprising the rare earth based hydrogen storage alloy according to claim 1.

23. A secondary battery comprising the rare earth based hydrogen storage alloy according to claim 1.